emwin bidirectional uses 66628 bytes of RO data

Hi
when i add GUI_UC_SetEncodeUTF8(); and GUI_UC_EnableBIDI(1); to my gui thread, gui__bidi2.o uses 66628 bytes of RO data.
I want to know if it's ok , or i have made a mistake.
and is there any way to reduce this ro data usage or even using external ram or nand flash instead?
Thanks a lot.